Diesel oil



Patented Jan. 7, 1941 PATENT OFFICE DIESEL on.

Edward R. Barnard, Chicago, Ill., assignor to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Application December 19, 1939, SerialNo. 310,017

11 Claims.

This invention relates to the lubrication of internal combustion engines and more particularly to internal combustion engines of the compression-ignition type commonly known as Diesel engmes.

Compression-ignition engines operate under compressions suificiently high to heat the air in the cylinder to a temperature above the ignition point of the fuel. In order to accomplish this it is necessary to employ compression ratios as high as 20:1 although in ordinary practice, com pression ratios of between 12: 1 and 14:1 are used. With compression ratios of this magnitude the compression pressure developed is about 500- 15 pounds per square inch. Pressures up to about 900 pounds per square inch have been employed experimentally but cannot be used in practice because of mechanical diiiiculties due in large measure to lubrication failure.

In Diesel engines the fuel is injected'into the combustion chamber at a slow uniform rate and extending over a considerable, portion of the power stroke in order to maintain a relatively constant pressure during combustion. Serious difiiculty has been encountered in maintaining proper lubrication in piston and piston rings because, due to the combustion being extended over a considerable period, the absorption of heat by the piston, which is much greater than in ordinary internal combustion engines, causes detrimental carbon deposition in the piston ring grooves and around the piston ring. Numerous mechanical expedients have been tried and employed to prevent undue carbonization of the lubricating oil, but perhaps the most important means which has been adopted for avoiding this carbonization is the selection of the lubricating oil employed for lubricating the Diesel engine. I-Ieretofore lubricating oils from paraffin base crude oils have been generally avoided because of their tendency to carbonize. The preferred Diesel engine lubricants have been oils of the naphthenic or coastal type due to the fact that they produce less carbon around the piston rings. But even these oils do not eliminate ring-sticking. Tests have shown that both paraffin-base oils and naphthenic-base oils form carbon which causes sticking of the piston rings, although oils of the 50 latter type produce somewhat less carbon than do oils of the former type.

An object of the present invention is to provide a lubricant which will satisfactorily lubricate the piston and other moving parts of Diesel engines and, which at the same time, will produce little or no carbon deposits on the piston and piston rings.

Another object of the present invention is to provide a naphthenic-base lubricant for Diesel engines which is characterized by a high viscosity index and by its tendency to produce little or no carbon deposits on the piston and piston rings.

Another object of the present invention is to provide a Diesel engine lubricant which will not cause ring-sticking.

I have discovered that the foregoing objects can be attained by providing a Diesel engine lubricant comprising a blend of a naphthenic or coastal lubricating oil, and a synthetic lubricating oil obtained by the catalytic polymerization of mono-olefins, particularly iso-olefins such as isobutylene at a temperature from about 0 F. to about 100 F. Under certain conditions where corrosion and/or feathering may occur it is highly desirable to add to the blend a small amount of sulfur or a sulfurized mineral oil, particularly a sulfurized high sulfur oil from a high sulfur crude oil, such as Winkler crude oil.

The naphthenic lubricating oil is preferably one having the following approximate specifications:

Viscosity at 210 F to 95 seconds Saybolt Viscosity index 0 to seconds Saybolt distillation temperature at one millimeter mercury pressure less than 600 F.

The naphthenic oil may be a fraction having the above characteristics or may be a mixture of naphthenic oils giving a blended oil of the above specifications.

The synthetic oil which I use is obtained by polymerizing liquid isobutylene with boron fluoride. In carrying out this part of the process, liquid isobutylene is maintained under pressure and cooled to a temperature, for example, of about 32 F., and about 0.1% to 2% of BFs is added with vigorous agitation. Excessive rise in temperature due to the heat of reaction may be avoided by efficient coo-ling. In order to facilitate agitation in handling and to assist in controlling the reaction I prefer to employa diluent such as hexane, liquid butane, propane, naphtha, etc., using a solution containing about 20% of isobutylene. I may also employ the butane-butylene fraction recovered from petroleum gases, espe-- cially those gases produced in the cracking of petroleum oils for the-manufacture of gasoline. This light fraction may contain about 10 to 25% butanes and normal butylenes.

It is preferred to subject the isobutylene to the action of the BF; catalyst for about 30 minutes and thereafter recover the heavy oily product by neutralization of the excess catalyst and removal of unreacted light hydrocarbons by evaporation. The resulting product is a viscous oil, a typical sample of which has the following characteristics:

Viscosity at 100 F 1538 seconds Saybolt Viscosity at 210 F 117 seconds Saybolt Viscosity index about 101 Flash point 250 F. Pour point 35 F.

- Viscosity at 210 F--. 50 to 100 seconds Saybolt Viscosity index to95 Pour point -35 F.

The blended Diesel lubricant comprises-a blend of from about 5% to about 95%, and preferably from about'25% to about of the isobutylene polymer residue and from about 5% to about 95%, and preferably from about 15% to about 75% of the naphthenic oil. To this blend there may be added from about 0.5% to about 4% and preferably from about 1% to about 2% of a sulfurized oil and preferably the sulfurization product of a lubricating oil of high natural sulfur content, such as a 'sulfurized Winkler stock to give the blend an active sulfur content 0 about 0.005% to about 0.5%.

An example of a desirable Diesel oil is a blend comprising about 30% of a naphthenic oil and about 70% of the isobutylene polymer residue to which has been added about 1.25% of a sulfurized winkler S. A. E. 10 stock. The specifications of the blend are tabulated below:

N aphthenic isobutylene oil polymer Blend Flash, F 45o 405 Saybolt Universal viscosity at 1 secon 1179 908 Saybolt Universal viscosity at 210 F.-seconds 70 75-80 74 Viscosity index 51 67. 2 00% distillation temperature at 1 mm. mercurygressure, F 578 Percent active ad ed suliur 0 02 The above blended Diesel engine lubricating oil was tested in a Buda engine equipped with cadmium-silver alloy bearings. After 300 hours operation the engine was inspected and the engine parts were found to be in perfect condition and an order of cleanliness and freedom from deposit attained. Another sample of this oil was tested in an eight cylinder, 2-stroke cycle General Motors Diesel engine in a locomotive doing service in a steel mill. After about 300 operating hours no oil deterioration was manifested, and no discoloration of the pistons observed. Using conventional Diesel lubricants. this period is suf- 2,227,692 of isobutylene, the remainder being principallyflcient to considerably discolor the pistons and to produce visible deposits of carbonaceous material in the ring belt. After more than 2000 hours of operation the condition of the engine was still highly satisfactory. Another example of a desirable blend is one in which 50 parts of a naphthenic oil was blended with 50 parts of the isobutylene polymer. The specifications of the naphthenic oil, the isobutylene polymer and of the blend are tabulated below:

Naphtlienic isobutylene oil polymer B 10nd Flash, F n. 395 330 350 Saybolt Universal viscosity at 100 F., seconds 570 600 584 Saybolt Universal viscosity at 210 F., seconds 56. 2 67. 3 61. 9 Viscosity index 24 91 as distillation temp. at 1 mm. of

mercury pressure 407 we The blended Diesel lubricant when tested in a Caterpillar Diesel tractor engine for 500 hours showed no carbon deposit on the piston and piston rings.

The 90% distillation temperature referred to herein is a measure of the tendency of lubricating oils to form carbon in internal combustion engines, and is determined by distilling a 200 cubic centimeter sample of the oil at 1 millimeter mercury pressure and determining the temperature of the vapor when 90% has distilled over. The test is described in detail by W. H. Bahlke et al. in the S. A. E. Journal, vol. 29, 1931 (page 215) The work of Bahlke et al. which was conducted with various oils both natural and synthetic showed that the carbon forming tendency of an oil was substantially in reverse proportion to the volatility of the oil. The volatility test as reported by Bahlke et al. supra has proved to be an accurate index of the carbon forming tendency of oils in internal combustion engine service.

The viscosity indices are determined by the Dean and Davis method described in Chemical and Metallurgical Engineering, vol. 36, 1929 (page 618).

It is to be understood that the blend herein described may have added to it other compounds such as for example, extreme pressure agents, antioxidants. and compounds such as lead oleate, alkyl chlorstearates, metal naphthenates, organic phosphites, for example tributyl phosphite, etc.

This application is a continuation-in-part of naphthenic base mineral oil having a 90% distillation temperature at one millimeter mercury Pressure of not more than about 600 F. and about 5% to about 95% of an isobutylene polymer from which the low boiling and the high molecular weight constituents have been removed, said isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about seconds. L

2. An improved Diesel engine lubricant comprilinga blend of about 5% to about 95% of a naphthenie base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F. and about 5% to about 95% of an isobutylene polymer having a Saybolt Universal viscosity'at 210 F. of from about seconds to about 100 seconds, said blend having a viscosity index greater than about 60.

3. A substantially non-carbon forming Diesel engine lubricant comprising a blend of about 5% to about 95% of a napthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F. and a Saybolt Universal viscosity at 210 F between about 50 seconds and 95 seconds, and from about 5% to about 95% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about 100 seconds and a viscosity index of from about 80 to about 95.

' 4. An improved Diesel engine lubricant comprising a blend of about 15% to about 75% of a naphthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F. and about 25% to about 85% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about 100 seconds, said blend having a viscosity index greater than about 60.

5. An improved Diesel engine lubricant comprising a blend of about 30% of a naphthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F. and about 70% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about 100 seconds, said blend having a viscosity index greater than about 60.

6. Asubstantially non-carbon forming Diesel engine lubricant comprising a blend of from about 30 parts to about 95 parts of a naphthenic oil having a viscosity at 210 F. of from about 50 1 seconds to about 95 seconds, a viscosity index of from about 0 to 35 and a 90% distillation temperature at 1 millimeter mercury pressure of not more than about 550 F. and from about 5 parts to about parts of an isobutylene polymer residue having a viscosity at 210 F. of from about '50 seconds to about 95 seconds, and a viscosity index of from about to about 95.

7. A substantially non-carbon forming Diesel engine lubricant comprising a blend of about 50 parts of a naphthenic oilhaving a viscosity at 100 F. of about 570 seconds, a viscosity at 210 F. of about 56, a viscosity index of about 24 and a distillation temperature at 1 millimeter mercury pressure of about 467 F. and about 50 parts of an isobutylenep ly residue vin a Vi cosity at 100 F. of about 600 seconds, a viscosity at 210 F. of about 67 seconds, and a viscosity index of about 91, said blend having a viscosity index of about 68 and a 90% distillation temperature at 1 millimeter mercury pressure of about 500 F.

8. An improved Diesel engine lubricant comprising a blend of about 5% to about of a naphthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F.

and about 5% to about 95% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about seconds, said'blend having a viscosity indexi greater than about 60, and from about 0.5% to about 4% of a sulfurized petroleum oil.

9. An improved Diesel engine lubricant comprising a blend of about 5% to about 95% of a naphthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of not more than about 600 F. and about 5% to about 95% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about 100 seconds, said blend having a viscosity index greater than about 60, and from about 1.0% to about 2% of a sulfurized high sulfur petroleum oil.

10. An improved Diesel engine lubricant comprising a blend of about 5% to about 95% of a naphthenic base mineral lubricating oil having a 90% distillation temperature at one millimeter mercury pressure of'not more than about 600 F. and about 5% to about 95% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of from about 50 seconds to about 100 seconds, said blend having a viscosity index greater than. about 60 and a small but suificient amount of a sulfurized petroleum oil to result in a blend of a sulfur content of from about 0.005% to about 0.5%.

11. An improved Diesel engine lubricant comprisinga blend of about 30% of a naphthenic base mineral lubricating oil having a 90% distillation temperature at about one millimeter mercury pressure of not more than about 600 F.,

and a Saybolt Universal viscosity at 210 F. of

about 80, and about 70% of an isobutylene polymer having a Saybolt Universal viscosity at 210 F. of Irom about 50 seconds to about 100 seconds and a viscosity index of about at least 80, and

about 1.25% of a sulfurized high sulfur mineral oil.

EDWARD R; BARNARD. 

